What are Conductors?
Conductors are objects that conduct electricity. This means that they permit flow of excess charge. Many metals are conductors. This is due to the lattice structure of metals, which allows for the free flow of charge through a sea of electrons.
What are Insulators?
Insulators are objects that insulate electricity. This means that they maintain a strong hold on their electrons, as well as ones they come into contact with. The structure of insulators prevents electrons from flowing, keeping the excess charge in place.
What is a Semiconductor?
Semiconductors are hybrids between conductors and insulators that can act as both.
What is a Superconductor?
Superconductors offer absolutely no resistance to the flow of charge, resulting in perfect conduction. Metals at extremely low temperatures become superconductors.
How do Electric Fields work within Conductors?
Excess charges in conductors reside on the outer surface, moving to spread themselves out as evenly as possible. The result is that the conductor has no net electric field. This is because electric field lines must begin and end on points of excess charge, which do not exist on the conductor. As the charge is spread evenly throughout the conductor, all the individual field vectors cancel each other out. This is the reason that radio waves cannot penetrate a metal tunnel: waves are not able to pass through without some form of field that exhibits some force.
In the above diagram, the vectors of attractive force all cancel each other out, as the conductor is a sphere. If there is no net electric force, there can be no net electric field since the field is a ratio of the force to the test charge.
F/Q = E
0/Q = 0